Comprehensive analysis of transcriptome profiles in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma is the second most deadly cancer with late presentation and limited treatment options, highlighting an urgent need to better understand HCC to facilitate the identification of early-stage biomarkers and uncover therapeutic targets for the development of novel therapies for HCC. METHODS: Deep transcriptome sequencing of tumor and paired non-tumor liver tissues was performed to comprehensively evaluate the profiles of both the host and HBV transcripts in HCC patients. Differential gene expression patterns and the dys-regulated genes associated with clinical outcomes were analyzed. Somatic mutations were identified from the sequencing data and the deleterious mutations were predicted. Lastly, human-HBV chimeric transcripts were identified, and their distribution, potential function and expression association were analyzed. RESULTS: Expression profiling identified the significantly upregulated TP73 as a nodal molecule modulating expression of apoptotic genes. Approximately 2.5% of dysregulated genes significantly correlated with HCC clinical characteristics. Of the 110 identified genes, those involved in post-translational modification, cell division and/or transcriptional regulation were upregulated, while those involved in redox reactions were downregulated in tumors of patients with poor prognosis. Mutation signature analysis identified that somatic mutations in HCC tumors were mainly non-synonymous, frequently affecting genes in the micro-environment and cancer pathways. Recurrent mutations occur mainly in ribosomal genes. The most frequently mutated genes were generally associated with a poorer clinical prognosis. Lastly, transcriptome sequencing suggest that HBV replication in the tumors of HCC patients is rare. HBV-human fusion transcripts are a common observation, with favored HBV and host insertion sites being the HBx C-terminus and gene introns (in tumors) and introns/intergenic-regions (in non-tumors), respectively. HBV-fused genes in tumors were mainly involved in RNA binding while those in non-tumors tissues varied widely. These observations suggest that while HBV may integrate randomly during chronic infection, selective expression of functional chimeric transcripts may occur during tumorigenesis. CONCLUSIONS: Transcriptome sequencing of HCC patients reveals key cancer molecules and clinically relevant pathways deregulated/mutated in HCC patients and suggests that while HBV may integrate randomly during chronic infection, selective expression of functional chimeric transcripts likely occur during the process of tumorigenesis.

Deep sequencing of the hepatitis B virus in hepatocellular carcinoma patients reveals enriched integration events, structural alterations and sequence variations.

Chronic hepatitis B virus (HBV) infection is epidemiologically associated with hepatocellular carcinoma (HCC), but its role in HCC remains poorly understood due to technological limitations. In this study, we systematically characterize HBV in HCC patients. HBV sequences were enriched from 48 HCC patients using an oligo-bead-based strategy, pooled together and sequenced using the FLX-Genome-Sequencer. In the tumors, preferential integration of HBV into promoters of genes (P < 0.001) and significant enrichment of integration into chromosome 10 (P < 0.01) were observed. Integration into chromosome 10 was significantly associated with poorly differentiated tumors (P < 0.05). Notably, in the tumors, recurrent integration into the promoter of the human telomerase reverse transcriptase (TERT) gene was found to correlate with increased TERT expression. The preferred region within the HBV genome involved in integration and viral structural alteration is at the 3'-end of hepatitis B virus X protein (HBx), where viral replication/transcription initiates. Upon integration, the 3'-end of the HBx is often deleted. HBx-human chimeric transcripts, the most common type of chimeric transcripts, can be expressed as chimeric proteins. Sequence variation resulting in non-conservative amino acid substitutions are commonly observed in HBV genome. This study highlights HBV as highly mutable in HCC patients with preferential regions within the host and virus genome for HBV integration/structural alterations.

Early experience with robot-assisted laparoscopic hepatobiliary and pancreatic surgery in Singapore: single-institution experience with 20 consecutive patients.

INTRODUCTION: Experience with robot-assisted laparoscopic (RAL) hepatobiliary and pancreatic (HPB) surgery remains limited worldwide. In this study, we report our early experience with RAL HPB surgery in Singapore. METHODS: A retrospective review of the first 20 consecutive patients who underwent RAL HPB surgery at a single institution over a 34-month period from February 2013 to November 2015 was conducted. The 20 cases were performed by three principal surgeons, of which 17 (85.0%) were performed by a single surgeon. RESULTS: The median age of patients was 56 (range 22-75) years and median tumour size was 4.0 (range 1.2-7.5) cm. The surgeries performed included left-sided pancreatectomies (n = 10), hepatectomies (n = 7), triple bypass with bile duct exploration for obstructing pancreatic head cancer with choledocholithiasis (n = 1), cholecystectomy for Mirizzi's syndrome (n = 1) and gastric resection for gastrointestinal stromal tumour (n = 1). The median operation time was 445 (range 80-825) minutes and median blood loss was 350 (range 0-1,200) mL. There was only 1 (5%) open conversion. There were 2 (10.0%) major morbidities (> Grade II on the Clavien-Dindo classification) and no 30-day/in-hospital mortalities. There was no reoperation for postoperative complications. The median postoperative stay was 5.5 (range 3-22) days. CONCLUSION: Our initial experience confirms the feasibility and safety of RAL HPB surgery.

Evolution of laparoscopic liver resection at Singapore General Hospital: a nine-year experience of 195 consecutive resections.

INTRODUCTION: We aimed to analyse the changing trends, safety and outcomes associated with the adoption of laparoscopic liver resection (LLR) at a single centre. METHODS: A retrospective review of patients who underwent LLR from 2006 to 2014 at our institution was performed. To explore the evolution of LLR, the study was divided into three equal consecutive time periods (Period 1: 2006-2008, Period 2: 2009-2011, and Period 3: 2012-2014). RESULTS: Among 195 patients who underwent LLR, 24 (12.3%) required open conversions, 68 (34.9%) had resection of tumours in the difficult posterosuperior segments and 12 (6.2%) underwent major (≥ 3 segments) hepatectomies. Median operation time was 210 (range 40-620) minutes and median postoperative stay was 4 (range 1-26) days. Major postoperative morbidity (> Grade II) occurred in 11 (5.6%) patients and 90-day/in-hospital mortality was 1 (0.5%). During the study, the number of LLRs performed showed an increasing trend (Period 1: n = 22; Period 2: n = 19; Period 3: n = 154). Other statistically significant trends were: (a) increase in malignant neoplasms resected; (b) increase in resections of difficult posterosuperior segments; (c) longer median operation time; and (d) decrease in open conversion rates. CONCLUSION: Over the study period, the number of LLRs increased rapidly. LLR was increasingly performed for malignant neoplasms and lesions located in the difficult posterosuperior segments, resulting in longer operation times. However, open conversion rates decreased, and there was no change in postoperative morbidity and other perioperative outcomes.

First experience with robotic spleen-saving, vessel-preserving distal pancreatectomy in Singapore: a report of three consecutive cases.

INTRODUCTION: The use of laparoscopic distal pancreatectomy (LDP) has increased worldwide due to the reported advantages associated with this minimally invasive procedure. However, widespread adoption is hindered by its technical complexity. Robotic distal pancreatectomy (RDP) was introduced to overcome this limitation, but worldwide experience with RDP is still lacking. There is presently evidence that RDP is associated with decreased conversion rate and increased splenic preservation as compared to LDP. METHODS: We conducted a prospective study on our initial experience with robotic spleen-saving, vessel-preserving distal pancreatectomy (SSVP-DP) between July 2013 and April 2014. RESULTS: Three consecutive patients underwent attempted robotic SSVP-DP. The indications were a 2.1-cm indeterminate cystic neoplasm, 4.5-cm solid pseudopapillary neoplasm and 1.2-cm pancreatic neuroendocrine tumour. For all three patients, the procedure was completed without conversion, and the spleen, with its main vessels, was successfully conserved. The median total operation time, blood loss and postoperative stay were 350 (range 300-540) minutes, 200 (range 50-300) mL and 7 (range 6-14) days, respectively. Two patients had minor Clavien-Dindo Grade I complications (one Grade A pancreatic fistula and one postoperative ileus). One patient had a Clavien-Dindo Grade IIIa complication (Grade B pancreatic fistula requiring percutaneous drainage). All patients were well at the time of reporting after at least six months of follow-up. CONCLUSION: Our preliminary experience with robotic SSVP-DP confirmed the feasibility of the procedure.